diff --git a/Makefile b/Makefile
index cf1ce0f..7484126 100644
--- a/Makefile
+++ b/Makefile
@@ -20,16 +20,12 @@ ifeq ($(FULL_WARNINGS), yes)
 endif
 
 ### SDL UI
-# ifeq ($(GUI), sdl)
 	CFLAGS += $(shell pkg-config --cflags SDL_gfx sdl12_compat)
 	LIBS += $(shell pkg-config --libs SDL_gfx sdl12_compat)
-# endif
 
 ### X11 UI
-# ifeq ($(GUI), x11)
 	CFLAGS += $(shell pkg-config --cflags x11 xext) -D_GNU_SOURCE=1 -DGUI_IS_X11=1
 	LIBS += $(shell pkg-config --libs x11 xext)
-# endif
 
 DOTOS = src/emu_serial.o \
 	src/emu_emulate.o \
@@ -109,7 +105,6 @@ install: all
 
 	install -m 755 -d -- $(DESTDIR)$(PREFIX)/share/applications
 	sed "s|@PREFIX@|$(PREFIX)|g" dist/x48ng.desktop > $(DESTDIR)$(PREFIX)/share/applications/x48ng.desktop
-# ifeq ($(GUI), x11)
+
 	install -m 755 -d -- $(DESTDIR)/etc/X11/app-defaults
 	install -c -m 644 dist/X48NG.ad $(DESTDIR)/etc/X11/app-defaults/X48NG
-# endif
diff --git a/src/emu_actions.c b/src/emu_actions.c
index 9f6460b..06d403c 100644
--- a/src/emu_actions.c
+++ b/src/emu_actions.c
@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 
+#include "emulator.h"
 #include "emulator_inner.h"
 #include "romio.h"
 #include "ui.h" /* ui__get_event(); ui__update_LCD(); */
diff --git a/src/emu_emulate.c b/src/emu_emulate.c
index f52c1b8..469db66 100644
--- a/src/emu_emulate.c
+++ b/src/emu_emulate.c
@@ -6,6 +6,7 @@
 #include "runtime_options.h" /* throttle */
 #include "ui.h" /* ui__get_event(); ui__adjust_contrast(); ui__update_LCD(); ui__draw_annunc(); */
 #include "debugger.h" /* enter_debugger, TRAP_INSTRUCTION, ILLEGAL_INSTRUCTION */
+#include "emulator.h"
 #include "emulator_inner.h"
 
 #define P_FIELD 0  /* unused? */
diff --git a/src/emu_init.c b/src/emu_init.c
index aea5041..10bf9e5 100644
--- a/src/emu_init.c
+++ b/src/emu_init.c
@@ -8,6 +8,7 @@
 #include <sys/types.h>
 
 #include "runtime_options.h"
+#include "emulator.h"
 #include "emulator_inner.h"
 #include "romio.h"
 
diff --git a/src/emu_memory.c b/src/emu_memory.c
index 877c639..ff9f1ba 100644
--- a/src/emu_memory.c
+++ b/src/emu_memory.c
@@ -4,6 +4,7 @@
 #include <sys/time.h>
 #include <unistd.h>
 
+#include "emulator.h"
 #include "emulator_inner.h"
 #include "romio.h"
 #include "ui.h" /* ui__disp_draw_nibble(); ui__menu_draw_nibble(); */
@@ -25,17 +26,13 @@
 
 #define DISP_INSTR_OFF 0x10
 
-extern int device_check;
-extern short port1_is_ram;
-extern long port1_mask;
-extern short port2_is_ram;
-extern long port2_mask;
-
 long nibble_masks[ 16 ] = { 0x0000000f, 0x000000f0, 0x00000f00, 0x0000f000,
                             0x000f0000, 0x00f00000, 0x0f000000, 0xf0000000,
                             0x0000000f, 0x000000f0, 0x00000f00, 0x0000f000,
                             0x000f0000, 0x00f00000, 0x0f000000, 0xf0000000 };
 
+display_t display;
+
 void ( *write_nibble )( long addr, int val );
 int ( *read_nibble )( long addr );
 int ( *read_nibble_crc )( long addr );
diff --git a/src/emu_register.c b/src/emu_register.c
index ab331af..26615d8 100644
--- a/src/emu_register.c
+++ b/src/emu_register.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "emulator.h"
 #include "emulator_inner.h"
 
 extern long nibble_masks[ 16 ];
diff --git a/src/emu_serial.c b/src/emu_serial.c
index 16807ff..53eb660 100644
--- a/src/emu_serial.c
+++ b/src/emu_serial.c
@@ -8,6 +8,7 @@
 #include <unistd.h>
 
 #include "runtime_options.h"
+#include "emulator.h"
 #include "emulator_inner.h"
 
 static int wire_fd;
diff --git a/src/emu_timer.c b/src/emu_timer.c
index 0d7eeae..4fa68f0 100644
--- a/src/emu_timer.c
+++ b/src/emu_timer.c
@@ -7,6 +7,7 @@
 #include <sys/time.h>
 
 #include "romio.h"
+#include "emulator.h"
 #include "emulator_inner.h"
 #include "debugger.h" /* used for in_debugger */
 
diff --git a/src/emulator.h b/src/emulator.h
index 69afbdd..b7a67eb 100644
--- a/src/emulator.h
+++ b/src/emulator.h
@@ -228,6 +228,12 @@ extern display_t display;
 
 extern saturn_t saturn;
 
+extern int device_check;
+extern short port1_is_ram;
+extern long port1_mask;
+extern short port2_is_ram;
+extern long port2_mask;
+
 /**************/
 /* emu_init.c */
 /**************/
diff --git a/src/main.c b/src/main.c
index 84e49a8..d357144 100644
--- a/src/main.c
+++ b/src/main.c
@@ -38,6 +38,31 @@ int main( int argc, char** argv ) {
     /**********/
     parse_args( argc, argv );
 
+    switch ( frontend_type ) {
+        case FRONTEND_SDL:
+            ui__disp_draw_nibble = ui_sdl__disp_draw_nibble;
+            ui__menu_draw_nibble = ui_sdl__menu_draw_nibble;
+            ui__get_event = ui_sdl__get_event;
+            ui__update_LCD = ui_sdl__update_LCD;
+            ui__adjust_contrast = ui_sdl__adjust_contrast;
+            ui__draw_annunc = ui_sdl__draw_annunc;
+            ui__init_LCD = ui_sdl__init_LCD;
+            init_ui = init_sdl_ui;
+            break;
+
+        case FRONTEND_X11:
+        default:
+            ui__disp_draw_nibble = ui_x11__disp_draw_nibble;
+            ui__menu_draw_nibble = ui_x11__menu_draw_nibble;
+            ui__get_event = ui_x11__get_event;
+            ui__update_LCD = ui_x11__update_LCD;
+            ui__adjust_contrast = ui_x11__adjust_contrast;
+            ui__draw_annunc = ui_x11__draw_annunc;
+            ui__init_LCD = ui_x11__init_LCD;
+            init_ui = init_x11_ui;
+            break;
+    }
+
     /*****************************************/
     /* handlers for SIGALRM, SIGPIPE */
     /*****************************************/
diff --git a/src/ui.c b/src/ui.c
index 1132cda..35de3f9 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -1,93 +1,10 @@
 #include "ui.h"
-#include "runtime_options.h"
 
-display_t display;
-
-extern void ui_sdl__disp_draw_nibble( word_20 addr, word_4 val );
-extern void ui_x11__disp_draw_nibble( word_20 addr, word_4 val );
-void ui__disp_draw_nibble( word_20 addr, word_4 val ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__disp_draw_nibble( addr, val );
-        case FRONTEND_X11:
-            return ui_x11__disp_draw_nibble( addr, val );
-    }
-}
-
-extern void ui_sdl__menu_draw_nibble( word_20 addr, word_4 val );
-extern void ui_x11__menu_draw_nibble( word_20 addr, word_4 val );
-void ui__menu_draw_nibble( word_20 addr, word_4 val ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__menu_draw_nibble( addr, val );
-        case FRONTEND_X11:
-            return ui_x11__menu_draw_nibble( addr, val );
-    }
-}
-
-extern int ui_sdl__get_event( void );
-extern int ui_x11__get_event( void );
-int ui__get_event( void ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__get_event();
-        case FRONTEND_X11:
-            return ui_x11__get_event();
-    }
-    return -1;
-}
-
-extern void ui_sdl__update_LCD( void );
-extern void ui_x11__update_LCD( void );
-void ui__update_LCD( void ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__update_LCD();
-        case FRONTEND_X11:
-            return ui_x11__update_LCD();
-    }
-}
-
-extern void ui_sdl__adjust_contrast( void );
-extern void ui_x11__adjust_contrast( void );
-void ui__adjust_contrast( void ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__adjust_contrast();
-        case FRONTEND_X11:
-            return ui_x11__adjust_contrast();
-    }
-}
-
-extern void ui_sdl__draw_annunc( void );
-extern void ui_x11__draw_annunc( void );
-void ui__draw_annunc( void ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__draw_annunc();
-        case FRONTEND_X11:
-            return ui_x11__draw_annunc();
-    }
-}
-
-extern void ui_sdl__init_LCD( void );
-extern void ui_x11__init_LCD( void );
-void ui__init_LCD( void ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return ui_sdl__init_LCD();
-        case FRONTEND_X11:
-            return ui_x11__init_LCD();
-    }
-}
-
-extern void init_sdl_ui( int argc, char** argv );
-extern void init_x11_ui( int argc, char** argv );
-void init_ui( int argc, char** argv ) {
-    switch ( frontend_type ) {
-        case FRONTEND_SDL:
-            return init_sdl_ui( argc, argv );
-        case FRONTEND_X11:
-            return init_x11_ui( argc, argv );
-    }
-}
+void ( *ui__disp_draw_nibble )( word_20 addr, word_4 val );
+void ( *ui__menu_draw_nibble )( word_20 addr, word_4 val );
+int ( *ui__get_event )( void );
+void ( *ui__update_LCD )( void );
+void ( *ui__adjust_contrast )( void );
+void ( *ui__draw_annunc )( void );
+void ( *ui__init_LCD )( void );
+void ( *init_ui )( int argc, char** argv );
diff --git a/src/ui.h b/src/ui.h
index b405e19..c717fc6 100644
--- a/src/ui.h
+++ b/src/ui.h
@@ -3,41 +3,66 @@
 
 #include "emulator.h" /* word_4; word_20; */
 
+/*************/
+/* functions */
+/*************/
+extern void ui_sdl__disp_draw_nibble( word_20 addr, word_4 val );
+extern void ui_x11__disp_draw_nibble( word_20 addr, word_4 val );
+
+extern void ui_sdl__menu_draw_nibble( word_20 addr, word_4 val );
+extern void ui_x11__menu_draw_nibble( word_20 addr, word_4 val );
+
+extern int ui_sdl__get_event( void );
+extern int ui_x11__get_event( void );
+
+extern void ui_sdl__update_LCD( void );
+extern void ui_x11__update_LCD( void );
+
+extern void ui_sdl__adjust_contrast( void );
+extern void ui_x11__adjust_contrast( void );
+
+extern void ui_sdl__draw_annunc( void );
+extern void ui_x11__draw_annunc( void );
+
+extern void ui_sdl__init_LCD( void );
+extern void ui_x11__init_LCD( void );
+
+extern void init_sdl_ui( int argc, char** argv );
+extern void init_x11_ui( int argc, char** argv );
+
 /*************************************************/
 /* public API: if it's there it's used elsewhere */
 /*************************************************/
 /*************************/
 /* used in: emu_memory.c */
 /*************************/
-extern void ui__disp_draw_nibble( word_20 addr, word_4 val );
-extern void ui__menu_draw_nibble( word_20 addr, word_4 val );
-
-/* extern void ui__draw_nibble( int c, int r, int val ); */
+extern void ( *ui__disp_draw_nibble )( word_20 addr, word_4 val );
+extern void ( *ui__menu_draw_nibble )( word_20 addr, word_4 val );
 
 /*****************************************/
 /* used in: emu_actions.c, emu_emulate.c */
 /*****************************************/
-extern int ui__get_event( void );
+extern int ( *ui__get_event )( void );
 
 /*****************************************************/
 /* used in: emu_actions.c, emu_emulate.c, debugger.c */
 /*****************************************************/
-extern void ui__update_LCD( void );
+extern void ( *ui__update_LCD )( void );
 
 /**************************/
 /* used in: emu_emulate.c */
 /**************************/
-extern void ui__adjust_contrast( void );
-extern void ui__draw_annunc( void );
+extern void ( *ui__adjust_contrast )( void );
+extern void ( *ui__draw_annunc )( void );
 
 /*********************************/
 /* used in: debugger.c, ui_sdl.c */
 /*********************************/
-extern void ui__init_LCD( void );
+extern void ( *ui__init_LCD )( void );
 
 /*******************/
 /* used in: main.c */
 /*******************/
-extern void init_ui( int argc, char** argv );
+extern void ( *init_ui )( int argc, char** argv );
 
 #endif /* !_X48_GUI_H */